Band knife guiding device

ABSTRACT

A longitudinally movable band knife of a leather splitting machine, is guided between edge portions of first and second guide plates. The lower guide plate is stationary, and the upper guide plate is mounted for universal movement about a fulcrum point so that the upper guide plate can be displaced about a first axis perpendicular to the cutting edge of the band knife, and about a second axis parallel to the cutting edge and intersecting the first axis at a fulcrum point so that the upper edge portion always has full contact with the moving band knife when a preferably self-locking biassing device turns the upper guide plate about the second axis to press with the respective guide edge portion against the band knife. Turning of the upper guide plate about a third axis perpendicular to the plane of the intersecting first and second axes, is prevented by blocking parts on the lower guide plate, projecting into openings in the upper guide plate located along the second axis.

United States Patent [191 Fingerle et al.

[ BAND KNIFE GUIDING DEVICE [75] Inventors: Karl Fingerle; Korb Juergen Haag,

both of Stuttgart-Hedelfingen, Germany [73] Assignee: Fortuna-Werke Maschinenfabrik AG, Stuttgart-Bad Cannstadt, Germany [22] Filed: Aug. 22, 1972 [21] Appl. No: 282,836

[30] Foreign Application Priority Data Sept. 3, 1971 Germany 2144132 [52] U.S. Cl. 83/820, 83/827 [51] Int. Cl..... 823d 55/08, B271) 13/10, 826d 1/54 [58] Field of Search 83/827, 820

[56] References Cited UNITED STATES PATENTS 426,684 4/1890 Prescott 83/827 3,068,734 12/1962 Braun 83/820 X 3,414,028 12/1968 McManama 83/827 June 18, 1974 Primary Examiner-Donald R. Schran Attorney, Agent, or Firm-Michael S. Striker [57] ABSTRACT A longitudinally movable band knife of a leather splitting machine, is guided between edge portions of first and second guide plates. The lower guide plate is stationary, and the upper guide plate is mounted for universal movement about a fulcrum point so that the upper guide plate can be displaced about a first axis perpendicular to the cutting edge: of the band knife, and about a second axis parallel to the cutting edge and intersecting the first axis at a fulcrum point so that the upper edge portion always has full contact with the moving band knife when a preferably self-locking biassing device turns the upper guide plate about the second axis to press with the respective guide edge portion against the band knife. Turning 0f the upper guide plate about a third axis perpendicular to the plane of the intersecting first and second axes, is we vented by blocking parts on the lower guide plate, projecting into openings in the upper guide plate located along the second axis.

18 Claims, 6 Drawing Figures 1 BAND KNIFE GUIDING DEVICE BACKGROUND OF THE INVENTION SUMMARY OF THE INVENTION It is one object of the invention to overcome the disadvantages of known guiding devices for band knives, and to provide a guiding device which assures absolutely precise guidance of the band knife irrespective of the condition of the cut material.

Another object of the invention is to provide a band knife guiding device which does not require difficult adjustments, and operates even if the band knife, or the guide edges of the guide plates, have been considerably worn.

With these objects in view, the present invention provides a guide means which, starting from a position par allel to another guide means, can be turned about a single fulcrum point;

An embodiment of the invention comprises first and second guide means, a longitudinally movable band knife located between the guide means and having opposite faces bounded by a cutting edge and slidably engaged by the first and second guide means, and mounting means secured to the first guide means and supporting the second guide means for universal movement about the fulcrum point. As a result, the second guide means can be angularly displaced about a first axis perpendicular to the cutting edge, and about a second axis parallel to the cutting edge and intersecting the first axis at the fulcrum point.

In a preferred embodiment, the fulcrum point is the center of a hemispherical concave seat in which a hemispherical convex member is guided for universal movement. It is advantageous to use the head of a threaded bolt as convex member engaging the hernispherical seat in the second guide means, while the threaded stem of the bolt is adjustably threaded into the first guide means. In this manner, an initial parallel position of the two guide means can be obtained.

In order to prevent the turning of the guide means about a third axis perpendicular to the plane formed by the intersecting first and second axes, blocking means are provided, preferably including an opening in one guide means, and a projecting member secured to the other guide means and engaging the opening.

In the preferred embodiment of the invention biassing means, preferably including self-locking wedgeshaped slides, are disposed between the first and second guide means for angularly displacing the second guide means about the second axis so that the edge portion of the second guide means is pressed against the band knife.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a plan view illustrating a first embodiment of the invention;

FIG. 2 is a cross-sectional view taken on line IIII in FIG. 1;

FIG. 3 is a cross-sectional view taken on line III-III in FIG. 1;

FIG. 4 is a plan view illustrating a modification of the embodiment of FIG. 1;

FIG. 5 is a cross-sectional view taken on line V-V in FIG. 4; and

FIG. 6 is a cross-sectional view taken on line Vl-VI in FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawing, corresponding parts are indicated by like reference numerals. Referring first to FIG. 1 and the corresponding cross sections of FIGS. 2 and 3, a band knife 5 is guided in the gap between two guide edge portions 3 and 4 of two guide means or guide plates 1 and 2. The guide edges of guide portions 3 and 4 are slightly spaced from the cutting edge 5a of the band knife 5. The edge portions 3 and 4 are preferably inserts consisting of sinter metal which is resistant to high frictional wear, while the metal of the guide plates 1 and 2 is selected for easy machining.

The band knife 5 moves in longitudinal direction, either in a reciprocating movement or in a continuous rotational movement. Friction losses occurring between band knife 5 and the slidingly engaged guide edge portions 3 and 4 are lower when the band knife 5 continu ously moves so that the same is generally constructed as an endless belt knife.

The lower guide means or guide plate 2 is preferably stationary, and secured to the frame of the machine, not shown. In order to assure a precise guiding of band knife 5, in accordance with the invention, the upper guide plate 1 is mounted for universal movement about a single fulcrum point K, which is located at the point of intersection of a first axis K, which is perpendicular to the cutting edge 5a and to the band knife 5, with a second axis K which is parallel to the cutting edge 50 and perpendicular to the first axis K The required pressure for turning the upper guide plate 1 about the axis K to a position in which the guiding edge portion 3 abuts the band knife 5, is, in the embodiment of FIGS. 1 to 3, obtained by a coil spring 6 whose ends abut the confronting inner faces of guide plates 1 and 2, as shown in FIG. 2. The spring 6 is preferably located under the first axis K as shown in FIG. 1 so that the pressure exerted by spring 6 against the upper guide plate 1 is symmetrical to the guide edge portion 3.

Due to the fact that the upper guide plate 1 can freely tilt about the fulcrum point K in all directions, the guide plate I automatically assume-s a position in which the guide edge portion 3 is parallel to the guide edge portion 4 of the stationary guide plate 2.

The top face of guide plate 1 has a hemispherical seat 9 which has a center located in the fulcrum point K, and a radius r. A bore 1a in guide plate 1 connects the seat 9 with the space between the guide plates 1 and 2. Guide plate 2 has a corresponding threaded bore 2a aligned with bore 1a and having a common axis A perpendicular to the plane in which the axes K and K are located.

A threaded bolt 8 has a threaded stem portion 80 threaded into the threaded bore 2a, another stem portion 8b surrounded by a spring 7 which abuts the confronting faces of guide plates 11 and 2, and a head por tion 8a provided with a hemispherical convex surface having the same radius r as the concave seat 9 and being concentric with the same at the fulcrum point K.

By adjusting bolt 8, the guide plate 1 can be precisely adjusted so that the guide edge portion 3 is parallel to the guide edge portion 4. The coil spring 7, which surrounds the stem of bolt 8, is not absolutely necessary but facilitates assembly of the mounting means 8, 9.

Evidently, the construction of the mounting means 8, 9 shown in FIG. 2 can be modified by providing a nut, not shown, having a hemispherical surface corresponding to the hemispherical surface 8d, guided on the hemispherical seat 9, and threaded to a threaded stem whose fixed head is located in a recess of guide plate 2.

While slight tilting of guide plate 1 about axis K, and K in accordance with the invention is desirable, turning of guide plate 1 about the axis A of the mounting means 8, 9 is undesirable, and is prevented by blocking means including sleeves l2 and 13 which are secured to guide plate 12 and are located along the axis K as shown in FIG. 1.

As best seen in FIG. 3, sleeve 12 or sleeve 13 (not shown in FIG. 3) has a stepped inner bore forming an annular shoulder 14 on which the head of a screw abuts when the threaded end portion 10a is screwed into the threaded bore 2b in the guide plate 12. The projecting sleeve 12 or 13 has the upper part thereof located in an opening 30 which has a wide cylindrical portion 30b and a narrow circular edge portion 30a surrounding the upper end of sleeve 12 with small tolerances. The wide portions 30b of the openings 30 permit tilting of the upper guide plate 1 about the axis K or K but the narrow circular edge 30a prevents turning of guide plate 1 about the axis A which is perpendicular to the plane formed by the axis K, and K Due to the fact that the blocking means 12 and 13 are located on the axis K the relative angular displacement of the guide plates 1 and 2 is reduced to a minimum.

As explained above, the spring 6 urges the upper guide plate 1 to turn about the axis K so that the guide edge portion 3 is pressed against the top face of the band blade 5. Spring 6 must be made very strong to prevent a tilting of guide plate 1 in clockwise direction when a very resistant material is being cut. However, a strong spring 6 increases the friction between the guide edge portion 3 and the band knife I during normal operations.

The embodiment illustrated in FIGS. 4 to 6 overcomes this disadvantage by providing self-locking biassing means for replacing the biassing spring 6. All other parts of the device shown in FIGS. 4 to 6 conform completely to the embodiment of FIGS. 1 to 3.

As shown in FIGS. 4, 5 and 6, the top face of the lower guide plate 2 is provided with a straight guideway 2c parallel to the axis K Two wedge-shaped slides 17 and 18, symmetrically arranged in opposite sides of the axis K are guided in the guideway 2a for movement along the same. Springs 19 and 20 have outer ends secured to the slides 17 and 18, and inner ends secured to an attaching means 21 located at the center of guideway 2a and secured to the top face of guide plate 2, as best seen in FIG. 6.

Springs 19 and 20 pull the slides 17 and 18 toward each other so that the wedge-shaped slides 17 and 18 act on the followers 15 and 16, which are secured to the upper guide plate 1 to tilt the upper guide plate 1 about the axis K to a position in which the guide edge portion 3 presses against the top face of the band knife 5. If the material which is being cut has an irregular density, the resistance encountered by the band knife 5 tends to turn the same together with guide edge portion 3 upward with guide plate 1 tilting about the axis K i.e. clock-wise on FIG. 5. However, the followers 15 and 16 are in self-locking engagement with the wedgeshaped slides 17 and 18, so that the guide plate 1 cannot be turned by the cut material in a clockwise direction about the axis K while counterclockwise turning of guide plate 1 due to the action of springs 19 and 20 is possible for pressing the band knife 5 against the lower guide edge portion 4. The self-locking biassing means lock the guide plate 1 rigidly against tilting away from the band knife 5. The arrangement of FIGS. 4, 5 and 6 reduces the frictional wear on the guide faces of the guide edge portions 3 and 4, as compared with the embodiment of FIGS. 1 to 3 where spring 6 has to pull so strongly as to prevent tilting away of guide plate 1 in clockwise direction when the material is very resistant, and acts with the same force on guide plate 1 during normal operational conditions so that very high friction prevails at the faces of the band knife 5 resulting in substantial wear.

The invention is not limited to the illustrated embodiments. For example, a single blocking sleeve 12, see FIGS. 1, 3 and 4, is sufficient to prevent turning of guide plate I about the axis A relative to guide plate 2. In the embodiment of FIGS. 4 to 6, the guideway can be arranged perpendicular to the cutting edge 5a and coinciding with the axis K,. In this event, only a single wedge-shaped slide is provided in the groove, biassed by a spring and engaging a follower secured to the guide plate 1. Instead of a wedge-shaped slide, an eccentric member or a biassed screw drive could be used.

It should be noted that the self-locking biassing device for guide plate 1 can also be used in an arrangement in which the upper plate 1 is turnable only about the axis K It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of guiding devices for flexible bands differing from the types described above.

While the invention has been illustrated and described as embodied in a guiding device for the band knife of a leather splitting machine, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

We claim:

1. Band knife guiding device comprising first and second guide means; a longitudinally movable band knife located between said guide means and having opposite faces bounded by a cutting edge and slidably engaged by said first and second guide means; and mounting means secured to said second guide means and supporting said first guide means for movement against said band knife about a fulcrum point so that said first guide means is free to become angularly displaced about a first axis perpendicular to said cutting edge, and about a second axis parallel to said cutting edge and intersecting said first axis at said fulcrum point.

2. Band knife guiding device as claimed in claim 1 comprising biassing means disposed between said first and second guide means for angularly displacing said second guide means about said second axis so that said second guide means is pressed against said band knife.

3. Band knife guiding device as claimed in claim 2 wherein said biassing means are located on the side of said second axis remote from said band knife.

4. Band knife guiding device as claimed in claim 3 wherein said biassing means includes spring means and is located in a third axis perpendicular to said first and second axes.

5. Band knife guiding device as claimed in claim 3 wherein said biassing means include self-locking means abutting said first and second guide means, and spring means biassing said self-locking means so that said first guide means is resiliently pressed against said band knife but cannot be turned from said band knife about said first axis by the cut material.

6. Band knife guiding device as claimed in claim 5 wherein said second guide means has a top face confronting the bottom face of said first guide means, and formed with a guide way parallel to said second axis; wherein said self-locking means includes at least one wedge-shaped slide guided in said guideway, a follower means secured to said bottom face of said first guide means and slidably engaging said wedge-shaped slide, and a spring urging said slide to move in said guideway so that said wedge-shaped slide acts on said follower means and on said first guide means to turn the latter about said second axis for pressing said first guide means against said band knife.

7. Band knife guiding device as claimed in claim 6 including two wedge-shaped slides in said guideway disposed symmetrically to said first axis, and spring means urging said slides toward each other; and wherein said follower means include two followers on said first guide means cooperating with said slides, respectively.

8. Band knife guiding device as claimed in claim 7 comprising an attaching means located in said guideway in the region of said first axis; and wherein said spring means include two springs having inner ends secured to said attaching means and outer ends secured to said slides, respectively.

9. Band knife guiding device as claimed in claim 1 wherein said mounting means include a hemispherical concave seat in one of said guide means, and a hemispherical convex member secured to the other guide means slidably engaging said seat, the centers of said hemispherical seat and of said hemispherical member coinciding at said fulcrum point.

Ml. Band knife guiding device as claimed in claim 1 wherein said second guide means has a bore perpendicular to the plane formed by said intersecting first and second axes; wherein said first guide means has a hemispherical concave seat; and wherein said mounting means include a stem portion secured in said bore, and a mounting portion having a hemispherical convex surface slidably engaging said seat, the centers of said hemispherical seat and of said hemispherical surface coinciding at said fulcrum point.

ill. Band knife guiding device as claimed in claim l0 wherein said mounting means includes a threaded bolt having said stem portion, and a head portion having said hemispherical convex surface; and wherein 'said first guide means has said seat on the outside thereof, and is formed with a bore therethrough opening in said seat aligned with said bore for receiving the portion of said stem adjacent said head portion.

12. Band knife guiding device as claimed in claim 10 wherein said mounting means includes a spring surrounding said stem and abutting the inner confronting surfaces of said first and second guide means.

13. Band knife guiding device as claimed in claim I and comprising blocking means connecting said first and second guide means spaced from said mounting means for blocking turning movement of said first and second guide means relative to each other about said third axis.

14. Band knife guiding device as claimed in claim 13 wherein said blocking means include at least one open ing in one of said guide means, and at least one blocking member secured to the other guide means and projecting into said opening.

15. Band knife guiding device as claimed in claim 14 wherein said blocking member includes a stepped sleeve having an annular shoulder, and a screw threaded into said second guide means and passing through said sleeve, said screw having a head abutting said annular shoulder.

16. Band knife guiding device as claimed in claim 14 wherein said opening in said first guide means has a wide portion and a narrow end portion; wherein said blocking member has a portion freely movable in said wide portion of said opening, and an end portion fitting into said narrow end portion of said opening with small tolerances, said narrow end portion being substantially located in a plane formed by said first and second axes passing through said fulcrum point.

17. Band knife guiding device as claimed in claim l3 wherein said blocking means include two blocking members secured to said second guide means and located in said second axis spaced from said fulcrum point, and two openings in said second guide means receiving the ends of said blocking members, respectively.

18. Band knife guiding device as claimed in claim 1 comprising biassing means disposed between said first and second guide means for angularly displacing said 8 coinciding at said fulcrum point; and comprising blocking means connecting said first and second guide means spaced from said mounting means for blocking turning movement of said first and second guide means relative to each other about said third axis passing through said fulcrum point. 

1. Band knife guiding device comprising first and second guide means; a longitudinally movable band knife located between said guide means and having opposite faces bounded by a cutting edge and slidably engaged by said first and second guide means; and mounting means secured to said second guide means and supporting said first guide means for movement against said band knife about a fulcrum point so that said first guide means is free to become angularly displaced about a first axis peRpendicular to said cutting edge, and about a second axis parallel to said cutting edge and intersecting said first axis at said fulcrum point.
 2. Band knife guiding device as claimed in claim 1 comprising biassing means disposed between said first and second guide means for angularly displacing said second guide means about said second axis so that said second guide means is pressed against said band knife.
 3. Band knife guiding device as claimed in claim 2 wherein said biassing means are located on the side of said second axis remote from said band knife.
 4. Band knife guiding device as claimed in claim 3 wherein said biassing means includes spring means and is located in a third axis perpendicular to said first and second axes.
 5. Band knife guiding device as claimed in claim 3 wherein said biassing means include self-locking means abutting said first and second guide means, and spring means biassing said self-locking means so that said first guide means is resiliently pressed against said band knife but cannot be turned from said band knife about said first axis by the cut material.
 6. Band knife guiding device as claimed in claim 5 wherein said second guide means has a top face confronting the bottom face of said first guide means, and formed with a guide way parallel to said second axis; wherein said self-locking means includes at least one wedge-shaped slide guided in said guideway, a follower means secured to said bottom face of said first guide means and slidably engaging said wedge-shaped slide, and a spring urging said slide to move in said guideway so that said wedge-shaped slide acts on said follower means and on said first guide means to turn the latter about said second axis for pressing said first guide means against said band knife.
 7. Band knife guiding device as claimed in claim 6 including two wedge-shaped slides in said guideway disposed symmetrically to said first axis, and spring means urging said slides toward each other; and wherein said follower means include two followers on said first guide means cooperating with said slides, respectively.
 8. Band knife guiding device as claimed in claim 7 comprising an attaching means located in said guideway in the region of said first axis; and wherein said spring means include two springs having inner ends secured to said attaching means and outer ends secured to said slides, respectively.
 9. Band knife guiding device as claimed in claim 1 wherein said mounting means include a hemispherical concave seat in one of said guide means, and a hemispherical convex member secured to the other guide means slidably engaging said seat, the centers of said hemispherical seat and of said hemispherical member coinciding at said fulcrum point.
 10. Band knife guiding device as claimed in claim 1 wherein said second guide means has a bore perpendicular to the plane formed by said intersecting first and second axes; wherein said first guide means has a hemispherical concave seat; and wherein said mounting means include a stem portion secured in said bore, and a mounting portion having a hemispherical convex surface slidably engaging said seat, the centers of said hemispherical seat and of said hemispherical surface coinciding at said fulcrum point.
 11. Band knife guiding device as claimed in claim 10 wherein said mounting means includes a threaded bolt having said stem portion, and a head portion having said hemispherical convex surface; and wherein said first guide means has said seat on the outside thereof, and is formed with a bore therethrough opening in said seat aligned with said bore for receiving the portion of said stem adjacent said head portion.
 12. Band knife guiding device as claimed in claim 10 wherein said mounting means includes a spring surrounding said stem and abutting the inner confronting surfaces of said first and second guide means.
 13. Band knife guiding device as claimed in claim 1 and comprising blocking means connecting said first and secOnd guide means spaced from said mounting means for blocking turning movement of said first and second guide means relative to each other about said third axis.
 14. Band knife guiding device as claimed in claim 13 wherein said blocking means include at least one opening in one of said guide means, and at least one blocking member secured to the other guide means and projecting into said opening.
 15. Band knife guiding device as claimed in claim 14 wherein said blocking member includes a stepped sleeve having an annular shoulder, and a screw threaded into said second guide means and passing through said sleeve, said screw having a head abutting said annular shoulder.
 16. Band knife guiding device as claimed in claim 14 wherein said opening in said first guide means has a wide portion and a narrow end portion; wherein said blocking member has a portion freely movable in said wide portion of said opening, and an end portion fitting into said narrow end portion of said opening with small tolerances, said narrow end portion being substantially located in a plane formed by said first and second axes passing through said fulcrum point.
 17. Band knife guiding device as claimed in claim 13 wherein said blocking means include two blocking members secured to said second guide means and located in said second axis spaced from said fulcrum point, and two openings in said second guide means receiving the ends of said blocking members, respectively.
 18. Band knife guiding device as claimed in claim 1 comprising biassing means disposed between said first and second guide means for angularly displacing said first guide means about said second axis so that said first guide means is pressed against said band knife; wherein said mounting means include a hemispherical concave seat in one of said guide means, and a hemispherical convex member secured to the other guide means slidably engaging said seat, the centers of said hemispherical seat and of said hemispherical member coinciding at said fulcrum point; and comprising blocking means connecting said first and second guide means spaced from said mounting means for blocking turning movement of said first and second guide means relative to each other about said third axis passing through said fulcrum point. 